GYP (Generate Your Projects) – a build automation tool (similar to CMake and Premake) to generate native IDE project files (e.g., Visual Studio, Xcode, etc.) from one configuration.
VisTrails – a scientific workflow and provenance management software with visual programming interface and integrated visualization (via Matplotlib, VTK).
Plotly – is a scientific plotting library for creating browser-based graphs.
SageMath – is a large mathematical software application which integrates the work of nearly 100 free software projects.
SymPy – a symbolic mathematical calculations package.
PyMC – python module containing Bayesian statistical models and fitting algorithms, including Markov chain Monte Carlo.
Numerical libraries
NumPy, a BSD-licensed library that adds support for the manipulation of large, multi-dimensional arrays and matrices; it also includes a large collection of high-level mathematical functions. NumPy serves as the backbone for a number of other numerical libraries, notably SciPy. De facto standard for matrix/tensor operations in Python.
Pandas, a library for data manipulation and analysis.
SageMath is a large mathematical software application which integrates the work of nearly 100 free software projects and supports linear algebra, combinatorics, numerical mathematics, calculus, and more.[12]
SciPy,[13][14][15] a large BSD-licensed library of scientific tools. De facto standard for scientific computations in Python.
ScientificPython, a library with a different set of scientific tools
SymPy, a library based on New BSD license for symbolic computation. Features of Sympy range from basic symbolic arithmetic to calculus, algebra, discrete mathematics and quantum physics.
Additional development packages
Beautiful Soup – package for parsing HTML and XML documents.
Cheetah – Python-powered template engine and code-generation tool.
Construct – python library for the declarative construction and deconstruction of data structures.
Genshi – template engine for XML-based vocabularies.
IPython – development shell both written in and designed for Python.
Jinja – Python-powered template engine, inspired by Django's template engine.
Kid – simple template engine for XML-based vocabularies.
Meson build system – software tool for automating the building (compiling) of software.
PyObjC – Python to Objective-C bridge that allows writing OS X software in Python.
Robot Framework – generic test automation framework for acceptance testing and acceptance test-driven development (ATDD).
Setuptools – package development process library designed to facilitate packaging Python projects by enhancing the Python distutils (distribution utilities) standard library.
GNAT – The GNAT programming chain tool (Ada language implementation in GNU gcc), as a GNATcoll reusable components for the applications (with or without PyGTK) and as a scripting language for the commands in the GPS programming environment.
Houdini highly evolved 3D animation package, fully extensible using python.
3DSlicer – a medical image visualisation and analysis software. Python is available for algorithm implementation, analysis pipelines, and GUI creation.
SPSS statistical software – SPSS Programmability Extension allows users to extend the SPSS command syntax language with Python.
NASA is using Python to implement a CAD/CAE/PDM repository and model management, integration, and transformation system which will be the core infrastructure for its next-generation collaborative engineering environment.[22][non-primary source needed] It is also the development language for OpenMDAO, a framework developed by NASA for solving multidisciplinary design optimization problems.
"Python has been an important part of Google since the beginning, and remains so as the system grows and evolves. Today dozens of Google engineers use Python."[23]
Reddit was originally written in Common Lisp, but was rewritten in Python in 2005.[24]
YouTube uses Python "to produce maintainable features in record times, with a minimum of developers".[25]
Enthought uses Python as the main language for many custom applications in Geophysics, Financial applications, Astrophysics, simulations for consumer product companies.
Pyjs – a framework (based on Google Web Toolkit (GWT) concept) for developing client-side Python-based web applications, including a stand-alone Python-to-JavaScript compiler, an Ajax framework and widget toolkit.
PyPy – Python (originally) coded in Python, used with RPython, a restricted subset of Python that is amenable to static analysis and thus a JIT.
Unladen Swallow – performance-orientated implementation based on CPython which natively executed its bytecode via an LLVM-based JIT compiler. Funded by Google, stopped circa 2011.